Application of hybrid coiled acoustic metamaterials in low frequency sound insulation
ZHAO Xinzhe1,2, LIU Guoqiang1,2*, XIA Dong1,2
(1 Institute of Electrical Engineering, Chinese Academy of Sciences,Beijing 100190, China;2 School of Electronic, Electrical and Communication Engineering, University of Chinese Academy of Sciences, Beijing 100049, China)
Abstract:
The audible noise generated by the transformer has a large impact on the station staff and nearby residents. This paper aims to study transformer noise and propose a method of noise reduction Firstly, the transformer noise is measured, and its spectral characteristics are analyzed according to the measurement results. A hybrid-coiled-type acoustic metamaterial unit is designed for the main noise frequencies which concentrated in the 400 Hz to 500 Hz regions. The inner acoustic waveguide of the hybrid-coil-type acoustic metamaterial unit has a length of more than 7 times longer than the unit size, and has an extremely high refractive index. The acoustic characteristics of the hybrid-coil-type acoustic metamaterial element are studied by finite element numerical calculation, and the sound transmission loss is calculated. It is found that it has a very high sound pressure reflection coefficient and the sound transmission loss reaches about 25 dB in the frequency range of 400 to 500 Hz. Experiments were performed using the impedance tube measurements, and the experimental results are compared with the finite element numerical data. And it is found that the two have high consistency. This work provides new ideas and research directions for low frequency sound insulation.
KeyWords:
transformer noise; low frequency; acoustic metamaterial; sound insulation; noise reduction